Induction draft apparatus.



A. FISCHER.

INDUCTION DRAFT APPARATUS.

APPLICATION IILIID JULY 9, 1912.

1,089,827. A Patented Mar. 10, 191

Attest:

MAtty ADALIBERT FISCHER, 0F PHILADELPHIA, PENNSYLVANIA.

INDUCTION DRAFT APPARATUS.

Specification of Letters Patent.

Application filed July 9, 1912.

Patented War. 10, 1914.

Serial No. 708,408.

To all whom it may concern:

Be it known that I, ADALBERT FISCHER, a subject of the German Emperor, residing at Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented certain new and useful Improvements in Induction Draft Apparatus, fully described and represented in the following specification and the accompanying drawings, forming a part of the same.

This invention relates to induction draft apparatus for furnaces, of that class in which a jet blower is provided for creating an artificial induced draft through the furnace by sucking the combustion gases from the furnace and discharging them against the atmosphere. A rotary centrifugal fan is usually employed for supplying atmospheric air to the jet blower under the required low pressure.

The object of the present invention is to reduce the power required to drive the fan or to otherwise supply the actuating medium under pressure, and this resultis accomplished in accordance with the invention by making use of a part of the gases of combustion from the furnace as the actuating or driving medium for the jet blow-- ers, the combustion gases for this purpose being best taken from a point between the combustion chamber of the furnace and the jet blower. By taking a part of the combustion gases to serve as the driving medium for the jet blower, the total quantity or volume of gases to be moved by the actie ating jet is reduced so that the necessary size of the jet blower itself and the power required to supply the driving medium thereto is thus also reduced correspondingly. With my improvement the amount of gas to be drawn from the furnace by the jet blower is the total amount of combustion gases less that part of the combustion gases used as the driving medium; whereas, with apparatus working in the old way, the jet blower has to draw from the furnace the total amount of the gases of combustion and to discharge the same plus the amount of cold air supplied by the fan as the driving medium. Then, too, since the action of the driving medium is by friction and depends on its volume rather than on its weight, therefore, by using the hot gases of combustion, which are much lighter per given voltime than atmospheric air, a further reduction in working power is accomplished. l urthermore, when cold atmospheric air is used as the operating medium in the jet blower, the tcn'iperaturc of the discharged gases 1s reduced and the natural draft impaired, whereas, with my apparatus making use of hot combustion gases as the driving medium there is little, if any, reduction in the temperature of the gases discharged from the blower, and the natural draft is thus not affected by reduction in temperature. An additional saving in power required to compress the driving medium is thus for this reason effected by my invention.

The accompanying drawing illustrates the application of my invention in an approved form to an ordinary boiler furnace.

111 said d awings, the jet blower is con nected with, and forms a continuation of, the discharge passage 10 through which the gases of combustion pass from the combustion chamber 11 of the furnace. The jet blower maybe of any siutable form such as that shown comprising a single jet nozzle 12 set to discharge upward into the converging portion 13 of the stack or uptake or a part thereof having the form of a Venturi tube. The driving medium is supplied to the nozzle 12 by a rotary centrifugal fan 1 lwhich is connected by a suction pipe 15 to draw a part of the gases of combustion to serve as the driving medium. As shown, the intake end of the supply pipe 15 is located in the discharge passage 10 below the jet blower and opens downward therein or against the direction of movement of the gases. I consider it best to take the gases of combustion which are to serve as the driving medium for the jet blower from a point between the combustion chamber of the furnace and the blower.

The operation of the apparatus shown will be understood from what has already been said.

It is to be understood that the invention is not to be limited to the exact construction and arrangement of parts in the apparatus shown but that it includes changes and modifications thereof within the claim.

\Vhat is claimed is:

The combination with a furnace, of a passage for the discharge of the combustion gases from the furnace comprising a portion having the form of a Venturi tube and including a converging part, a jet nozzle set In testimony whereof, I have hereunto set to dlscharge lnto sa-ld converglng part my hand, 1n the presence of tWo subscrlbmg of Sitld port-1011 of the chschztrge passage, wltnesses.

and means for supplying under pressure to ADALBERT FISCHER. 5 the jet nozzle a part of the combustion gases WVitnesses:

taken from a point between the combustion D. W. HILDRETH,

chamber of the furnace and the jet nozzle. I SIMON W. SNYDER.

Copies of this patent may be obtained. for five cents each, by addressing the Commissioner of Patents, Washington, 1). G." 

